Winding for electrical apparatus



0. T. FARRY WINDING FOR ELECTRICAL APPARATUS May 18, 1948.

Filed April 2, 1945 mvsmoa: 8H5 T F'ARRY BY ATTORNEY.

Patented May 18, 1948 WINDING FOR ELECTRICAL APPARATUS Otis T. Farr-y, University City, Mo., assignor to Wagner Electric Corporation, St. Louis, Mo., a

corporation of Delaware Application April 2, 1945, Serial No. 586,180

6 Claims. 1

This invention relates to windings for transformers, reactors, and the like, in which there are a suitable number of transpositions of conductor elements, one of its objects being to provide an economical method and means of preventing short circuits between conductor elements at cross-over points which might otherwise result from damage to the insulation on the elements due to relative motion of said elements either during the formation or handling of the winding or parts thereof, or during operation of the apparatus.

In alternating current inductive apparatus, such as choke coils, transformers, and the like, it is often necessary to employ a conductor having a large cross-sectional area in order to carry the desired current without undue heating. If a single conductor of large cross section were used, heavy eddy currents would be set up in the conductor with resultant losses. For this, as well as mechanical reasons, it has been cus tomary to employ a composite conductor com posed of a number of insulated smaller conductors or strands connected in parallel.

If such strands were of fiat ribbon and wound concentrically, the strands would be of differing length with the result that the total current would not be dividided evenly among them, and this unequal division would be augmented by the fact that the self-inductance caused by leakage flux is different in the various strands. To avoid this condition it is common practice to make transpositions to even the length of the strands of the conductors.

By transposing adjacent strands, pressure points between them may be created at one or both sides of the point of crossing, and also relative motion between strands adjacent crossover points may be produced not only in the process of forming the winding, but on account of unequal heating of the individual strands and varying magnetic forces effective thereon in the operation of a transformer or other device embodying the winding. It is accordingly necessary that insulating material, in addition to the insulation covering of the strands, be provided whereby abrasion of the latter due'to such relative motion, may not establish short circuits between adjacent strands at transposition points. My invention is directed to improved means for this purpose.

strand conductor showing insulation inserts positioned at transposition points in accordance with my invention; t

Figure 3 is an elevational view of one of said inserts;

Figure 4 illustrates a section of a transformer or reactor coil;

Figure 5 is a side elevational view of a transposition in a 2-strand conductor and showing application of my improved insulating means; and

Figure 6 is a sectional view taken substantially along the line 6-9 of Figure 2.

The drawings indicate windings of the disc or pancake type and parts thereof, Figure i illustrating a part of a common form of transformer winding made up of spaced apart coils of this time.

A suitable form of insulation insert is illustrated in Figure 3 and consists of a sheet it of paper or cloth, preferably varnish impregnated, and provided with laterally opening slots l9 and, i9" dividing the insert into segments 58 and it connected by the tongue element to. Figure 5 illustrates the application of such an insert at the transposition point of strands 2t and 2d! of a 2-strand conductor, the transposition being made at the offset bends 25 in the conductor elements formed after winding one coil and preparatory to winding the adjacent coil. Alter forming these bends the elements are transposed, during which operation the insulation insert is placed inposition, each slot receiving one of the conductor elements, segment it of the insert extending between the conductor elements at one side of the transposition point, and segment l6 extending between said elements at the other side of said point. It will be noted that the connecting tongue 20 ofthe insert is of such dimension relative to the spacin between the inner edges of the conductor element at the point of transposition that after the insert is placed in position and the transposition completed, substantial displacement of the insert, either laterally or longitudinally from the desired position, is prevented.

Figure 4 illustrates a portion of a transformer winding consisting of coils formed from Z-strand- Coils i and 2 are wound on. a l'lla' conductors. chine capable of winding two disc coils from a single length of conductor. The numerals i and 8 indicate the portions of the conductor constituting the connection between these coils, which connectors are transposed and provided with an insulation insert, showing or this insert at this Particular point being omitted from Figure 4 for the purpose of clarity. The adjoining pair of coils l, l are formed in the same manner and pair I; 2 of the connecting elements being transposed and provided with insulation insert I as shown. These connecting extensions are secured, by soldering or otherwise, to the conductor of the previous pair at the point indicated by dotted line 9. The numeral I 0 indicates an extension of the initial turn of coil 1 for coimection to the apparatus terminal and the transposition 1; 8, which may be referred to as the inside transposition, is adJacent the transformer core insulating tube 32. The transposed connection between coil pair I, 2 and coil pair 3, 4 is on the outside of the winding. In the manner described a winding can be constructed embodying any number of coils.

thereof, said insulating sheet having two spaced apart openings each receiving one of said conductor elements.

Figures 2 and 6 illustrate the assembly with the strands of a 4-strand conductor of the three insulation inserts of the kind illustrated in Figure 3, which are required at the transposition point in such a conductor. In this figure the segments of theleft-hand insert, which receives and insulates strands l3 and H, are designated by the numerals It and it; the segments of the insert to the right (for strands i2 and I3) by the numerals I I and I1; and the segments-01' the re-' maining insert (for strands II and I!) by the numerals l8 and it. As indicated, segment I! overlies segment l6 and segment i8 overlies seg rnent l|'.\ Thisresults in double thickness of insulation at two areas but if it should be preferred that this be avoided in forming a transposition in a multi-strand conductor, a sheet of insulation may be employed which corresponds to that shown in Figure 3 except that it is longer and is provided with the requisite number of pairs of slots properly positioned to receive each two adjacent strands at the points where they cross each other.

If the dotted lines in Figure 2, which indicate the ends of insulation segments I6 and I1, were omitted this figure would illustrate the extended insert above mentioned. s

This invention is not limited to transposition in windings consisting of disc coils but it is adaptable to any winding arrangement requiring transposition and located in plane or cylindrical surface. For example, the cross connectors between points ofequal potential in a largeD. C. armature winding. may be insulated as indicated in Figure 2. l

Having fully described my invention, that which I claim as novel and desire to protect by individually insulated strands which are transposed at one or more points and which lie side by side throughout their length between transposi- 4. In a winding for an electrical apparatus in which at least two conductor elements of the winding lie side by side and are transposed at one or more'points, a sheet of insulating material having parts positioned between said conductor elements at each side of a transposition point to prevent contact between said elements in areas by side'and are transposed at one or more points,

a sheet of insulating material having parts positioned between said conductor elements at each side of a transposition point to prevent contact between saidelements in areas immediately adjacent said point at each side thereof, said sheet tion points, a sheet of insulatingmaterial having parts positioned between the strands at each side being provided with oppositely disposed slots positioned at the point of crossing of the conductor elements and through each of which one ofsaid elements extends, each conductor element having a portion engageable by the portion of the sheet between the inner ends of said slots to prevent longitudinal movement of the insulatdng sheet in one direction. I

6. In an electrical conductor comprising two ribbon-shaped strands which are transposed at one or more points and faces of which lie side by side throughout their length between transposition points, each of said strands being bent at a transposition point, a sheet of insulating .material having parts positioned between said strands at each side of a transposition point to prevent contact between said strands in the areas immediatelyadjacent said point at each side thereof, said insulating sheet being provided with slots each receiving one of said strands and positioned at a point adjacent a bend therein.

4 OTIS T. FARRY.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES IVV'ATENTS Number Name Date 1,658,970 Colburn Feb. 14, 1928 1,684,164 Weiller Sept. 11, 1928 1,761,046 Pfautz. June 3, 1930 2,157,031 Stephens May 2, 1939 2,195,986 I Goddard Apr. 2, 1940 2,215,422 Glerum Sept. 17, 1940 2,318,361 Bischof! May 4, 1943' 

